At present, in a metro vehicle project, each side of every passenger carriage is provided with four doors. The four doors are respectively provided with an emergency unlocking device and an emergency alarming device aside, all of which are to alarm under an emergency situation.
However, such design with relatively same functions not only occupies the resources, but also increases the difficulty in arranging an interface for equipment in the carriage overall. Moreover, the user experience of a passenger cannot be improved.